A heart attack—also called myocardial infarction or MI—occurs when an area of heart muscle is completely deprived of blood, and the heart muscle cells die.
A heart attack may result when plaque inside the heart arteries breaks open or ruptures, forming a clot that significantly blocks blood flow through the artery.
A plaque is made up of cholesterol, white blood cells, calcium, and other components, and it is surrounded by a fibrous cap. This fibrous cap may tear or rupture if blood suddenly flows faster or if the artery suddenly narrows. A tear or rupture signals the body to repair the injured artery lining—much as it might heal a cut on the skin—by forming a blood clot to seal the area. A blood clot that forms in an artery can completely block blood flow to the heart muscle and cause a heart attack.
Symptoms of a heart attack include:
Heart attack symptoms do not go away with rest or nitroglycerin.
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